Preheat the oven to 180C.,Grease the inside of the tart pan with a thin and even layer of butter (not listed).,Then dust with a layer of cake flour (not listed).,Allow the butter to return to room temperature.,______,Sift together the cake flour and baking powder.,Slice the banana for decoration into 1 cm slices and sprinkle with lemon juice.,[Caramel Sauce] Add the sugar and 2 tablespoons of water to a pan and put on a high heat.,When the mixture turns brown, stop the heat, add 3 tablespoons of water and mix together.,Add the butter into a bowl and cream with a whisk.,Then add the powdered sugar, brown sugar and salt and mix well.,Add the almond flour into the mixture and mix.,Add the egg yolks a little a time and stir in after each addition.,Pour in the banana puree and mix again.,Add the sifted cake flour and baking powder in 2-3 goes and fold in with a rubber spatula.,Pour the batter into the tart pan and flatten out the surface.,Arrange the bananas from Step 3 on top and press them into the batter a little.,Bake for 25 minutes at 180C.,Then turn the temperature down to 160C and bake for a further 10 minutes.,Check to see if it's done by inserting a skewer into the center.,If it comes out clean, it's ready!,Sift over some powdered sugar, pour over the caramel sauce and serve!,Instead of making the caramel sauce yourself, you can also buy it at the shop.,This cake is okay just out of the oven but tastes much better after a day when the flavours have had a chance to settle.